Process of swaging dental crowns.



Patented May 2|, |90I.

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@MTE STATES PATENT Ormea.

BENJAMIN l. BREWER AND IILLIAM M. H. BURFEIND, OF SAN FRANCISCO, CALIFORNIA.

PROCESS OF SWAGING DENTAL CROWNS.

SEGIFICATION forming part of Letters Patent No. 674,834, dated May 21, 1901.

Implication filed October 30, 1900. Serial No. 34,958. (No specimens.)

To @ZZ- whom t may concern,.-

Beit known that we, BENJAMIN B. BREWER and WILLIAM M. H. BURFEIND, citizens of the United States, residing at San Francisco,

in the county of San Francisco and State of California, have invented a certain new and useful Process of Swaging Dental Crowns, of which the following is a specification.

Our invention relates to an improved procro ess of swaging denial crowns, the object of our invention being to provide a method by which dental crowns can be swaged to the desired form with a less expenditure of time and labor than heretofore and also with greater accuracy in the result, so that the gold crown produced by our improved method may be free from wrinkles and correspond perfectly to the form to which it is swaged.

In the accompanying drawings, Figure lis zo a central vertical section of the mold, showing the crown supported therein preparatory to pouring the molten lead around the same. Fig. 2 is a similar view of the mold, showing the molten lead around the crown as it ap- 5 pears prior to swaging. Fig. 3 is a similar View of the mold, showing the same as it appears after swaging. Fig. 4 is an enlarged perspective View of the leaden jacket removed from the mold after swaging and with the 3o crown inclosed therein. Fig. 5 is an enlarged perspective View showing the method of applying the nippers to the leaden jacket to remove the same, and Fig. 6 is a similar view of the jacket expanded by means of said nipners and removed from the crown.

Referring to the drawings, a represents the upper cylindrical portion of a mold, having dowel-pins I), which t into recesses c in the lower cylindrical portion d. fis a lead thimble which is placed in the bottom of the cavity of the mold, and upon said thimble is supported a gold cup g, which is to be swaged into a dental crown. A stick of wood Z is used for holding the cup into place and also prevents the molten lead entering the cup. Molten lead or other soft metal is now poured around the gold cup, as shown at h, up to the upper edge of said cup. After the lead has solidified the stick is withdrawn and there 5o is inserted in the cup the form t, previously prepared, to which the crown is to be swaged.

A disk 7c, of lead or paper, fitting within the cylindrical section a, is now placed upon the top of the lead jacket h and of the cup g, and the end of the punchj is inserted above said disk. The whole of this apparatus is now placed upon a suitable anvil and the punch is driven down by a heavy hammer until the lead has been compressed or swaged in the cylindrical mold to such an extent that t-he 6o opening or recess n in the leaden thmblef has been completely closed. Then the ap- 4 paratus is lifted from the anvil, and the thimble, the jacket inclosing the crown, and the disk are forced out of the mold. The disk and thimble will then fall off the jacket.

An important feature of our invention consists in the method of removing the jacket Without deforming the crown. To accomplish this object, we make use ot' a pair of 7o nippers p, having their cutting edges, as shown at o, beveled on both sides. Such cutting edges are applied to the flat ends of the cylindrical jacket in a radial direction and are forced together in the axial direction of the jacket, the inner points just avoiding the outer face of the crown, which is embedded in said jacket. The cutting action of the nippers has the effect of pressing the lead outward and expanding the leaden jacket. 8o Three or four cuts or recesses vr are made in the leaden jacket in this manner, and it will then be found that the lead is sufficiently expanded or opened out from the center to permit the crown, with the form therein, to drop out. The form t', which is composed of readilyfusible material, is then melted out of the crown, and the operation of swaging the crown is completed.

We claim- 9o 1. The process of swaging dental crowns which consists in pouring molten soft lead around a cup to form a jacket, compressing said jacket to swage the cup containing a form into the desired shape, and removing said jacket, substantially as described.

2. The process of swaging dental crowns which consists in pouring molten soft metal around a cup, inserting a forminto the cup, pressing the soft-metal jacket upon the cup roo to swage the same, cutting said jacket in a direction parallel with the axis thereof so as away the jacket, and melting out the form, substantially as described.

In witness whereof we have hereunto set our hands in the presence of two subscribing 15 witnesses.

BENJAMIN B. BREWER. WILLIAM M. H. 'BURFEINIL Witnesses:

F. M. WRIGHT, Z. A. DANIELS. 

